An EL display device that uses the Electro luminescence (hereinafter referred to as “EL”) of a luminescent material is gathering attention as a display device offering a faster response speed in comparison to a liquid crystal display device, and also having a wider viewing angle.
This type of display device has a configuration including, for example, a TFT substrate formed by thin film transistors (TFTs) provided on a support body, which is formed by a glass substrate and the like, and a plurality of light emitting elements, such as organic EL (OLED) elements, connected to the TFTs.
However, in general, this type of light emitting element is susceptible to the influence of moisture, oxygen and the like, and the characteristics thereof deteriorate due to a reaction to small amounts of moisture, oxygen or the like, thus impairing the life of the display device.
Here, to prevent the infiltration of moisture or oxygen into the light emitting element, for example, Thin Film Encapsulation (TFE) technology is known for encapsulating the light emitting element by forming a sealing film in which inorganic layers and organic layers are alternately layered (see PTL 1, for example).
The inorganic layer has a moisture-proof function to prevent the infiltration of moisture and functions as a barrier layer. Meanwhile, the organic layer is used as a buffer layer (a stress relief layer) and mainly performs stress relief of the inorganic layer, and leveling by burying steps in the surface of a light emitting element layer including the light emitting elements, in a display region.
The film formation of the inorganic layer is performed, for example, by Chemical Vapor Deposition (CVD), vacuum vapor deposition, sputtering, or the like.
On the other hand, the organic layer is formed, for example, by an ink-jet method, in which a liquid organic material is applied to the display region, and the liquid organic material is then cured.
However, in a case where wet-spreading of the liquid organic material is large, the organic layer is exposed to the outside. This may lead to such a deterioration in the reliability of the display device that moisture or the like infiltrates from an exposed surface of the organic layer, a connection defect arises because of terminals covered by the organic layer, and the like.
Here, as disclosed in PTL 1, for example, as an organic layer stopper, a plurality of frame-shaped banks, which regulate the wet-spreading of the liquid organic material, are formed outside of a flattening film that covers the TFTs, surrounding the display region as multiple banks.
In PTL 1, it is disclosed that a stopper pattern, which functions as the organic layer stopper and is formed of protrusions, is provided in triple banks, for example, so as to surround a first control pattern and a second control pattern that surround the display region.